1. Field of the Invention
The invention relates to an integrated circuit design technique, more particularly to a method of fabricating integrated circuits.
2. Description of the Related Art
It is common for a system to use multiple hardware units with similar functionalities in order to enhance operational efficiency of the system. Examples include incorporating a number of receivers in a communication system to enhance reception and incorporating a number of processors in a computer system in order to accelerate computing speed and enhance computing capability. The number of required hardware units depends on the level and purpose of the particular application.
There are three conventional ways of providing multiple hardware units in a system.
In a first conventional method, a set of photomasks is utilized to fabricate dies, each containing a single hardware unit, and then a desired number of dies are packaged together so as to form an integrated circuit chip that contains multiple hardware units, such is commonly referred to as “system in package”. Although the cost incurred when fabricating the photomasks is reduced, packaging costs are high. In addition, communication between the hardware units in each integrated circuit chip is limited by the number of pads contained in each die in the integrated circuit chip, which has an adverse effect on transmission speed.
In a second conventional method, for each particular application purpose, a distinct set of photomasks is prepared for use in fabricating integrated circuit chips each including a corresponding number of hardware units as required for that particular application purpose. Although communication among the hardware units in each integrated circuit chip is relatively less problematic, it is relatively costly to produce a set of photomasks custom-made for each particular application purpose.
In a third conventional method, a set of photomasks is used to fabricate integrated circuit chips, each containing a single hardware unit, and then the desired number of integrated circuit chips are mounted on a printed circuit board (PCB) so as to form the desired system. Although this method reduces the complexity of photomask production and packaging, communication among the hardware units is limited by the number of pins on each integrated circuit chip. In addition, packaging costs are still significant.